Band saw pulley drive



June 21, 1932. p AVILLA 1,863,822

BAND SAW PULLEY DRIVE Original Filed Jan. 8, 1930 '4& 5 ,0

IN V EN TOR.

2 r afifizr I ATTORNEYS.

Patented June 21, 1932 UNITED STATES,"

PATENT OFFICE.

PHILIP AVILLA, F DALY GITY, CALIFORNIA, ASSIGNOR OF TWO-FIFTHS TO T. E.

HIMLE, OF BURLINGAME, CALIFORNIA {BAND SAW IPULLEY DRIVE Applicationfiled January 8, 1930, Serial No. 419,359. Renewed September 21, 19 3 1.

This invention relates to a band saw and especially to the pulleyswhereby the band saw is supported and driven.

A band saw is usually supported and driven by means of a pair of crownedpulleys. Crowned pulleys are very satisfactory providing the saw isbeing handled bya skilled operator and provided the pulleysarepositively aligned but if any misalign- 10 ment develops, for instancethrough wear caused by end thrust through one orthe other of thepulleys, or by bending orwarplng of the frame in which the pulleys arejournalled trouble will develop as the saw will tend to work is beingpassed through the saw. I

The object of the present invention is to automatically return the sawblade if forced to one side or another-of the pulley surface and whichwill retain the saw blade -regard wise.

tion in the accompanying drawing, 1n

w hich to Fig. 1 is a side elevation of a band-saw, said elevation beingpartially broken away and sectioned to show the band saw driving andsupporting pulleys,

Fig. 2 is'an enlarged sectionof the rim of the idling pulley, and p vFig. 3 is an enlarged section of the rim of the driving pulley. 7

Referring to the drawing in detail, A in,-

40 upon which the work is supported while come OK or jump the pulleysthe moment the slightest excess pressure is applied while supporting anddriving the saw, and especially, to provide pulley surfaceswhich w1llless of misalignment of the pulleys or other-.

.dicates a base member, B a frame, C the table ment disclosed in thepresent instance being the, shape of the pulley faces.

' The idling pulley is best illustrated in Figs. 1 and It is an ordinarypulley provided with a crown face as indicated by the lines 2 and 3, butit difiers from the ordinary crown pulley in being provided with anexterior annular flange or rim 4, the function of which will behereinafter described.

The driving pulley is best illustratedin 0' Figs. 1 and 3. It isprovided with a flatpulley surface such as shown at 5, an annulargroove6 and a second flat surface which has a diameter slightly less than thediameter presented by the flat surface 5. In other 55 words, the surface7 is slightly stepped or reduced in diameter with relation to thesurface 5. This pulley is also provided with an annular rim or flangesuch as indicated at aa. The main function of the flanges 4 and 4a beingthat of retaining the saw blade from complete removal from the pulleysif it should happen to-be pulled towards the operator in the directionof arrow at for instance when removing work from the'saw.

- The crown surface of the pulley indicated The invention is shown bywayof illustraat 9 normally retains the saw blade at the center or thehighest point of the crown.

'- This is the natural'function of a crown pulley as a belt or saw bladesuch as here illustrated 6 has a tendency to climb an inclined surface.This function is well known. The center line of the idling pulley or inother words the peak of the crown will under normal conditions alignwith the center line indicated 5 at 8-8 on the driving pulley and theblade will thus be retained in the position indi cated at 9a. The teethof the blade indicated at 10 aligning with the annular groove .6 so asto prevent flattening or injury of the teeth, the groove beingsuificiently deep to prevent contact of theteeth with the pulleysurface. The position of the blade indicated at88 in Fig. 3 is thenormal running position of V the blade and as the surface upon which theblade rides is flat, as here indicated, there is y no tendency for theblade to moveto one side of the pulley or the'other. It may happen thatan operator in passing workthrouglr the saw applies an excess pressure,in that instance the blade might be crowded downwardly over the inclinedsurface indicated at 2 on the idling pulley but it has no tendency tocrawl or move over on the flat surface indicated at 5 hence the momentexcess pressure isrelieved the blade immediately climbs up the inclinedsurface 2 of the idling pulley thereby returning it to normal or runningposition. It is also possible particularly where an unskilled operatoris running the saw that the work may be pulled away from i not possiblycome off orv jump the pulley due the saw in the direction of arrowa toorapidly or may hang up on the work. In that case, the blade would bepulled downwardly over the inclined surface 8 of the idling pulleyiand imight possibly shift slightly in the same direction on the drivingpulley. In fact, in extreme cases it might be pulled against the annularflanges indicated at 4 and etc without doing any damage as it could tothese flanges. The saw will even under such extreme conditions return tonormal position as the flat surface 5 presents a larger diameter thanthe surface 7 and as the surface 3 is inclined in an upward directionthe two surfaces Will co-operate to return the blade to normal orrunning position.; Pulley surfaces for supporting and ,driving the sawhave accordingly been providedwhichwill not only automatically returnthe blade to normal running position demand.

employed may be such as the manufacturer may decide, or varyingconditions or uses may Having thus describedmy invention, What I claimand desire to secure by Letters Patent 1. In a structureof the characterdescribed a frame, a pair of pulleys mounted on the frame, one of saidpulleys presenting a crown pulley surface and the other a flat pulleysurface, and a band saw supported by the pulleys.

2. V Ina structure of the characterdescribed a frame, a pair of pulleysmounted on the frame, one ofsaid pulleys presenting a crown pulleysurface. and the other a flat pulley surface, a band saw supported bythe pulleys,

and an annular flange-formed on oneside of each pulley and projectingabove the pulley surfaces.

a frame, anidlerand a driving pulley mountfed therein, the idler pulleypresenting a 3.1119. structure the character described 7 crown pulleysurface and the driving pulley a .flat pulley surface, and a band sawsupported and driven by the pulleys.

4. In a structure of the character described a frame, an idler and adriving pulley mounted thereon, said driving pulley presenting a pair offlat annular pulley surfaces of unequal diameter and having an annulargroove formed between said surfaces, said idler pulley presenting acrown pulley surface and a band saw supported and driven by the pulleys,the teeth of the saw normally registering'with the annular groove in thesurface of the driving pulley to. prevent the teeth of'the saw fromcontacting'with the ulley surface- 5. In a structure of the characterde-- scribed a frame, an idler and a driving pulley mounted thereon,said driving pulley presenting a pair of flat annular pulley surfaces ofunequal diameter and having an annular groove formed between saidsurfaces, saididler pulley presenting a crown pulley surface and abandsaw supportedand driven by the pulleys, the teeth of the saw normallyregistering with the annular groove in the surfaceof the driving pulley.to prevent the teeth of. the saw from contacting with the pulleysurface, and an annular flange formed on one side of each pulley andprojectingabove the adjacent pulleysurfaces. I v l 6. In. a, structureof the character/described, a frame,-a pairof pulleys-mounted on theframe,o ne of said pulleys presenting lo) a crownpulley surfaceand-theother a flat pulley surface, and a band saw supported by the pulleys,said last-named pulley having an annular groove formed :in its face atone: side of the flat pulley surface to'prcventthe teeth of the saw fromcontacting withthe pulley surface. 7. In astructureof the character de-'scribed, a frame, an idler and a driving pul-. ley mounted thereon,,saiddriving pulley presenting a pair of annular pulleysurfaces of unequaldiameter, one of said surfaces being flat and said surfaces beingseparated by an annular groove,saididler pulley presenting a crownpulley surface, and a band saw sup 115. ported and driven by thepulleys, the teeth of the saw normally registering with'the annulargroove in the surface of the driving pulley to prevent the teeth of thesaw from contacting with thepulley surface. g PHILIP AVILLA.

